Backscattering Raman spectroscopy using multi-grating spatial heterodyne Raman spectrometer.

Spatial heterodyne Raman spectrometry (SHRS) is a spectral analysis technique used to study material structures and compositions. We propose a multi-grating SHRS system that uses a multi-grating module rather than the single grating used to terminate each arm in traditional spatial heterodyne spectrometry (SHS). The proposed system not only retains the advantages of traditional SHS but also resolves the mutual limitation between system spectral range and resolution. The increased spectral range and resolution that can be achieved in detection are dependent on the number of sub-gratings used in the module. A verification system was built using 130 gr/mm and 150 gr/mm sub-gratings and calibrated. Under different experimental conditions (including laser power, integration time, container material and thickness, pure and mixed samples, and standoff experiments), the backscattered Raman spectra of different types of targets (including organic solutions, inorganic powders, and minerals) were tested. The multi-grating SHRS shows good performance for broad spectral range and high-resolution Raman detection.